Expandable unit cell and intraluminal stent

• US RE44,763 E1
• Filed: 02/01/2002
• Issued: 02/11/2014
• Est. Priority Date: 04/01/1998
• Status: Expired due to Term

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Phan, Loc X., Eury, Robert, Pomerantseva, Irina, Froix, Michael, Dinh, Linh A.
• Primary Examiner(s): Stewart, Alvin J.
• Application Number:
  US10/061,458
• Time in Patent Office: 4,393 Days
• Field of Search: 623/1.15, 623 11- 12, 623/1.11, 623/1.12, 623/1.16, 623/11.11, 623/12.11
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91525 within the whole structure different bands showing different meander characteristics, e.g. frequency or amplitude
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/9155 Adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2002/91566 connected trough to trough
• CPC Class Codes: A61F 2002/91575 connected peak to trough

Abstract

A unit cell for use in a medical device, such as a stent, is disclosed along with a description of a stent formed from a plurality of unit cells and for use in the treatment of restenosis or other vascular narrowing. The unit cell is designed and configured for uniform radial expansion with minimal axial shortening and recoil, and is selectively variable in flexibility and expendability.

Claims

1. A unit cell for use in a stent adapted to be expanded to conform to the dimensions of a vessel, comprising;

(i) an elongate connecting bar extending in a direction normal to the direction of stent expansion,

(ii) associated with each end of said connecting bar, a pair of arms including a first arm and a second arm, each arm being attached to the connecting bar associated end at an inner arm end for pivotal movement away from one another with stent expansion, said first and second arms having outer arm ends which are moved outwardly, with respect to the connecting bar, with such pivotal movement, and

(iii) an expandable looped member connecting the outer arm ends in each pair of first and second arms, said looped member having an axial extremity which moves axially inwardly, with respect to the associated connecting bar end, component length as measured in an axial direction from an axial outward extremity to an axial inward extremity, wherein the axial component length reduces with stent expansion,

said arms and expandable looped members being constructed and dimensioned so that the radial axial outward distance traveled by the arms'"'"' outer ends in each pair of first and second arms is approximately equal to the axial inward distance traveled by reduction in length of the axial component length of the associated looped member extremity, as the stent is expanded.

2. The unit cell of claim 1, wherein said first and second arms in each pair are connected to said looped members through a shoulder member.

3. The unit cell of claim 2, wherein said shoulder member is a U-shaped, N-shaped or W-shaped shoulder member.

4. The unit cell of claim 1, wherein said looped members have an undulating configuration.

5. A stent adapted to be expanded to conform to the dimensions of a vessel, comprising a plurality of unit cells, each unit cell composed of

(i) an elongate connecting bar extending in a direction normal to the direction of stent expansion,

(ii) associated with each end of said connecting bar, a first arm and a second arm, each arm being attached to the associated connecting bar end at an inner arm, for pivotal movement away from one another with stent expansion, said first and second arms having outer arm ends which are moved outwardly, with respect to the connecting bar, with such pivotal movement, and

(iii) an expandable looped member connecting the outer arm ends in each pair of first and second arms, said looped member having an axial extremity which moves axially inwardly, with respect to the associated connecting bar end, component length as measured in an axial direction from an axial outward extremity to an axial inward extremity, wherein the axial component length reduces with stent expansion,

said arms and expandable looped members being constructed and dimensioned so that the axial outward distance traveled by the arms'"'"' outer ends in each pair of first and second arms is approximately equal to the axial inward distance traveled by reduction in length of the axial component length of the associated looped member extremity, as the stent is expanded.

6. The stent of claim 5, wherein said first and second arms in each pair are connected to said looped members through a shoulder member.

7. The stent of claim 6, wherein said shoulder member is a U-shaped, N-shaped or W-shaped shoulder member.

8. The stent of claim 5, wherein said axial extremity in each of said looped members has an undulating configuration.

9. The stent of claim 5, wherein said plurality of unit cells is connected to one or more axially adjacent plurality of unit cells by at least one connecting segment extending between two axially adjacent axial extremities.

10. The stent of claim 9, wherein each plurality of unit cells includes between 3-500 unit cells.

11. The stent of claim 9, wherein the stent has an expansion ratio, taken as the diameter of the stent after expansion to the diameter before expansion, of between 1-10.

12. The stem of claim 11, wherein the expansion ratio is varied by varying the axial length, taken as the distance between axial extremities in a unit cell, of the unit cells in each plurality of unit cells.

13. The stent of claim 11, wherein the expansion ratio is varied by varying the number of unit cells in each plurality.

14. The stent of claim 9, wherein said connecting segment is a U-shaped looped segment.

15. The stent of claim 5, which further includes an outer stent surface on which a polymer stent is carried, said stent and polymer stent designed for coexpansion in response to an applied force.

16. A stent having a plurality of openings therethrough, the stent comprising a plurality of serpentine circumferential bands, adjacent serpentine circumferential bands connected one to the other, the serpentine circumferential bands including first serpentine circumferential bands of a first shape and second serpentine circumferential bands of a second shape different from the first shape, every first serpentine circumferential band being adjacent to a said second serpentine circumferential band and every second serpentine circumferential band being adjacent to a said first serpentine circumferential band, distal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, proximal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, at least one opening not bounded by a said second serpentine circumferential band.

17. The stent of claim 16 wherein adjacent first and second serpentine circumferential bands are connected one to the other via a plurality of longitudinally extending connectors.

18. The stent of claim 17 wherein a said first serpentine circumferential band has a width which differs from the width of a said second serpentine circumferential band.

19. The stent of claim 17 wherein the serpentine circumferential bands comprise alternating peaks and troughs, the adjacent first and second serpentine circumferential bands being connected only via the longitudinal connectors, a portion of the longitudinal connectors extending between peaks of the first and second serpentine circumferential bands, a portion of the longitudinal connectors extending between troughs of the first and second serpentine circumferential bands.

20. The stent of claim 16 wherein a said first serpentine circumferential band has a width which differs from the width of a said second serpentine circumferential band.

21. The stent of claim 16 wherein adjacent serpentine circumferential bands are connected one to the other via one or more longitudinally extending connectors.

22. A stent having a plurality of openings therethrough, the stent comprising a plurality of serpentine circumferential bands, adjacent serpentine circumferential bands connected one to the other, the serpentine circumferential bands including first serpentine circumferential bands of a first shape and second serpentine circumferential bands of a second shape different from the first shape, every first serpentine circumferential band being adjacent to a said second serpentine circumferential band and every second serpentine circumferential band being adjacent to a said first serpentine circumferential band, at least one said first serpentine circumferential band adjacent to and connected to another said first serpentine circumferential band, distal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, proximal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, wherein adjacent first and second serpentine circumferential bands are connected one to the other via a plurality of longitudinally extending connectors, wherein a said first serpentine circumferential band has a width which differs from the width of a said second serpentine circumferential band,

wherein the serpentine circumferential bands comprise alternating peaks and troughs, the adjacent first and second serpentine circumferential bands being connected only via the longitudinal connectors, a portion of the longitudinal connectors extending between peaks of the first and second serpentine circumferential bands, a portion of the longitudinal connectors extending between troughs of the first and second serpentine circumferential bands.

23. A stent having a plurality of openings therethrough, the stent comprising a plurality of serpentine circumferential bands, adjacent serpentine circumferential bands connected one to the other, the serpentine circumferential bands including first serpentine circumferential bands of a first shape and second serpentine circumferential bands of a second shape different from the first shape, every first serpentine circumferential band being adjacent to a said second serpentine circumferential band and every second serpentine circumferential band being adjacent to a said first serpentine circumferential band, at least one said first serpentine circumferential band adjacent to and connected to another said first serpentine circumferential band, distal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, proximal most openings of the stent being at least partially bounded by a said first serpentine circumferential band and at least partially bounded by a said second serpentine circumferential band, wherein adjacent serpentine circumferential bands are connected one to the other via one or more longitudinally extending connectors,

the longitudinally extending connectors comprising first longitudinal connectors of a first length and second longitudinal connectors of a second length less than the first length.

24. The stent of claim 23 wherein the serpentine circumferential bands comprise alternating peaks and troughs, the first longitudinal connectors extending between peaks of some adjacent serpentine circumferential bands and between troughs of other adjacent serpentine circumferential bands, the second longitudinal connectors extending between peaks and troughs.

25. A stent comprising a plurality of sections, each section comprising a plurality of loop members, the loop members arranged to form first bands extending about the circumference of the stent, each first band comprising alternating peaks and troughs, each peak separated from a trough adjacent thereto and connected thereto by a bent portion of a loop member, first bands which are adjacent one another within a section separated one from the other by a second band, each second band connected to each first band adjacent thereto, said second bands shaped differently from said first bands, a distal most first band of one section adjacent to and connected to a proximal most first band of another section by a longitudinally extending connecting segment, the longitudinally extending connecting segment connected at a first end to a distal portion of the distal most first band and connected at a second end to a proximal portion of the proximal most first band, wherein a first band of a section is located at an end of the stent.

26. The stent of claim 25 wherein first and second bands which are adjacent one another are connected one to the other via longitudinally extending connectors.

27. The stent of claim 26 wherein each second band is in the form of two adjacent, out of phase, interconnected serpentine structures.

28. A stent comprising a plurality of circumferential serpentine bands including first circumferential serpentine bands and second circumferential serpentine bands, the first circumferential serpentine bands having a width in excess of the width of the second circumferential serpentine bands, circumferential serpentine bands which are adjacent one another connected one to the other, at least one second serpentine circumferential band immediately adjacent to and connected to another second serpentine circumferential band by a straight longitudinal connector.

29. The stent of claim 28 wherein adjacent circumferential serpentine bands are connected one to the other via one or more longitudinal connectors.

30. The stent of claim 29 wherein the first circumferential serpentine bands have an amplitude in excess of the amplitude of the second serpentine bands.

31. The stent of claim 30 wherein each first circumferential serpentine band is adjacent a second circumferential serpentine band and each second circumferential serpentine band is adjacent a first circumferential serpentine band.

32. The stent of claim 28 wherein each first circumferential serpentine band is adjacent a second circumferential serpentine band and each second circumferential serpentine band is adjacent a first circumferential serpentine band.

33. The stent of claim 28 wherein the first circumferential serpentine bands have an amplitude in excess of the amplitude of the second serpentine bands.